title: Cosolvent-free polymer gel dosimeters with improved dose sensitivity and resolution for x-ray CT dose response.
abstract: This study reports new N-isopropylacrylamide (NIPAM) polymer gel recipes with increased dose sensitivity and improved dose resolution for x-ray CT readout. NIPAM can be used to increase the solubility of N, N'-methylenebisacrylamide (Bis) in aqueous solutions from approximately 3% to 5.5% by weight, enabling the manufacture of dosimeters containing up to 19.5%T, which is the total concentration of NIPAM and Bis by weight. Gelatin is shown to have a mild influence on dose sensitivity when gels are imaged using x-ray CT, and a stronger influence when gels are imaged optically. Phantoms that contain only 3% gelatin and 5 mM tetrakis hydroxymethyl phosphonium chloride are sufficiently stiff for dosimetry applications. The best cosolvent-free gel formulation has a dose sensitivity in the linear range (~0.88 H Gy(-1)) that is a small improvement compared to the best NIPAM-based gels that incorporate isopropanol as a cosolvent (~0.80 H Gy(-1)). This new gel formulation results in enhanced dose resolution (~0.052 Gy) for x-ray CT readout, making clinical applications of this imaging modality more feasible.
authors.affiliation: Department of Chemical Engineering, Queen's University, Kingston, K7L 3N6, Canada.
authors.forename: J N M
authors.initials: JN
authors.lastname: Chain
authors.forename: A
authors.initials: A
authors.lastname: Jirasek
authors.forename: L J
authors.initials: LJ
authors.lastname: Schreiner
authors.forename: K B
authors.initials: KB
authors.lastname: McAuley
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry; D005782:Gels; D011108:Polymers / Q000737:chemistry*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012995:Solubility; D014057:Tomography, X-Ray Computed; D014867:Water / Q000737:chemistry
chemical_list: D000178:Acrylamides; D005782:Gels; D011108:Polymers; D014867:Water; D005780:Gelatin; C067295:N-isopropylacrylamide